Haigh Diagram
The Haigh diagram shows the allowable stress amplitude versus mean stress for a given number of load cycles. It helps in designing components under combined static and dynamic loading.
Physical-Chemical Mechanism
The Haigh diagram plots stress amplitude (Δσ) against mean stress (σm) for a given number of cycles. It accounts for both static and dynamic stresses on a material.
Metallurgical Relevance & Welding Risks
The diagram is important for determining allowable stresses in components under cyclic loading. Overstress can lead to cracks and failure. The weld must stay within the allowable region of the Haigh diagram.
Shop Practice & Instructions
To use the Haigh diagram correctly:
1. Determine the mean stress (σm) and stress amplitude (Δσ) of the components.
2. Identify the number of cycles for the specific application.
3. Check that the stresses are within the allowable range of the Haigh diagram.
4. Adjust welding parameters if needed to ensure the weld can withstand the loading.